Using conditional compilation symbols in MVC views

Question

In "Properties" of my project I have the following:

I want to check if TEST symbol exists, and only then, do some things. So I did what you see in the picture below and in the class it works. However this does not work in the views.

The text in this block is gray even if TEST is defined!

How can I cause it work if TEST is defined?

Answer 1

Rather than specify the compiler flag in web.config as per the accepted answer (which also requires specifying the compiler version in web.config, which is a non-standard location) I went with the following:

Add a method to a base class shared by my models

public bool IsDebugBuild 
{ 
    get
    {
        #if DEBUG
        return true;
        #else
        return false;
        #endif
    }
}

Use that method in my views

if (mm.IsDebugBuild) {
    <div class="debug">
    // Do Stuff
    </div>
}

Answer 2

The problem is related to the fact that views are only compiled when you run your application so the TEST symbol that you defined is no longer applied by the compiler because it has no knowledge of it.

Assuming that you are using C# you need to configure the compiler to use the TEST symbol when building the views and for this you need to override its configuration in Web.config using the following:

<system.codedom>
  <compilers>
    <compiler
      language="c#;cs;csharp"
      extension=".cs"
      type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
      compilerOptions="/define:TEST"
      warningLevel="1" />
  </compilers>
</system.codedom>

The important part is that you define compilerOptions="/define:TEST". The rest of the configuration you need to adapt to your specific needs, for example switch between .NET 2.0 or .NET 4.0.

If you apply this directly in the Web.config it will work but will define TEST every time. So what you should really do is use Web.config transformations so that the symbol is only applied for the correct build configurations.